The New York City medical examiner’s office says the cause and manner of death for a 14-year-old autistic boy who was missing for months cannot be determined.

Avonte Oquendo disappeared from his Queens school on Oct. 4, setting off a massive search that included extensive searches of subway tunnels and regular announcements over the public-address system at subway stations.

His remains were found in the East River in January, several miles from where he vanished.

Oquendo had a form of autism that made him nonverbal.

The family’s lawyer has filed a notice of claim, the first step in suing the city.